Identifying Your Specimens

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Why this note?

Identification is a many-step process. It starts in the field when you are gathering information on a plant you plan to collect. If you are lucky, the work done with the specimens gathered will be confirming the preliminary identifications done at the time of collection. This note is to guide you on the uncertain path to a proper identification.

• You will need
• Catalogs versus keys
• In the field
• In the lab or at home
• Turning in your specimens

You will need:

1. Field identification books
2. Access to the internet
3. Patience and time

Catalogs versus keys

Most likely, all of the plants you will collect will already be described. I will give an A and a glowing letter of recommendation to anyone who collects and describes a new species for this course. Both would be truly deserved. However, most will have to get their A's by discovering plants for themselves, if not for everyone. Since there are hundreds of thousand plants described and many species look like other, related species, how do you identify them? Two kinds of resources are most valuable: Catalogs and keys.

A catalog is simply a listing, with varying amounts of description and depiction, of the plants that belong to some defined group: the flowering plants of Tennessee, the trees of North America, common wildflowers, plants found in special habitats such as swamps or springs, etc. One finds the plant of interest by flipping through the pages (or webpages) until satisfied that you have found the right description or that your plant is not in the catalog. Catalogs are almost never complete. Usually, they are arranged so that similar plants are listed together, which means that you can decide among similar alternatives without worrying that other, more similar alternatives are somewhere else in the catalog. Sometimes the species are grouped by some useful criterion so that you can eliminate lots of the catalog at the start. Many wildflower books group by color, so that you don't have to search among lots of blue flowers if yours is red. Be careful, though. The division between white and light blue is sometimes hard to make, so be generous when deciding on which sections might be relevant.

Some catalogs and websites are organized further by the addition of a key. There are lots of variants, but the idea is to narrow the number of possible plants in successive steps until only one plant is left. It is identification by exclusion. Keys are like a branching path. You start down the path until you get to a point where the your path ends and two or more new paths begin. You decide which to follow based on some information about the plant. Is it flowering or not? Does it have alternate, opposite, or whorled leaves? The first question produces a bifurcation and the second a trifurcation. Some keys stick to bifurcations and are called dichotomous. Some are trichotomous and some don't worry about how many choices are given. Good keys have unambiguous choices (Plant has alternate leaves, go to step 2; plant has any other leaf arrangement, go to 214). Bad keys have difficult choices (Leaf margin deeply indented, go to 2; leaf margin slightly indented, go to 214). Most keys are mixtures of good and bad choices. In addition, many keys will use unfamiliar terms. If so, check for some explanation in the introduction to the catalog, look for a glossary, or go to my page on morphology and search the web for help. Often you can get a description with pictures.

In the field:

There are many good field guides, but no guide is good for all occasions. You may wish to purchase a good tree guide and a good wildflower guide. If you have an interest in ferns or other non-flowering plants, they are usually in separate guides. When buying a guide, look for clear pictures or illustrations, range maps, keys, and compactness (lugging huge books puts a damper on the fun).

If possible, identify the species in the field. This cuts down on later work. It also give you an idea of what should be collected. Make sure you collect enough material to allow display all of the important characteristics on the mounted specimen. This will cut down on errors or second visits to the field to get additional material.

If you can't identify the species in the field, don't just give up. There are many more resources on the web and you will have to confirm the identification in any case. Collect and worry later.

In the lab or at home:

Once you return from the field, you might have a preliminary identification of the specimen. What to do next? You will have to confirm the identification using the resources available to you. These are: the web, books in the TSU and Nashville libraries (or what ever local libraries are accessible), and your instructor. The order should represent the order in which you use the resources.

I have found lots of websites and there is a listing on the course page. Using them will take some time, but will speed up as you find the ones you like and get familiar with the terminology and important characteristics. You can do this while preserving the material if you have collected enough material.

Many public libraries have good horticultural sections with lots of plant descriptions. A problem arises if you want to have the material at hand when working with the books. Try not to take the books from the library but use them there. I have found that, if I clear it with the librarian, I have been allowed to bring the plant material into the library and work in the library (as long as it is not so much material at any one time - the lesser the better- and I promise to leave the table and floor without any plant refuse). This is the preferred means for us. Remember that there are lots of students in the class and that everyone will want access to those books.

If you are stumped, come to me and we will try together. This is not a guarantee that we will be successful but don't give up before all avenues have been explored.

Turning in your specimens:

Remember that you don't have to wait until the last day to hand specimens in. In fact, it is better if you come to me as soon as you have them identified so that you can check them over (that way, there are no surprises on the last day). Just bring them to me with the notebook and we will go over the specimen to see if it is presented correctly, check the identification, and enter it onto your list of identified specimens. At the end of the course, I may ask to keep some specimens but it is completely your choice to donate you specimens or not. It will not affect your grade in any way. I may also ask to keep the notebook or a copy of it. If asked, presenting a copy is a requirement and not handing it in will affect the grade. A description of the notebook is found on the collection page.

This kalanchoe has an unusual leaf margin. It develops plantlets that can fall off and establish clones. This means that when you find one plant, you usually find lots of them. It can form the entire ground cover in some forests. However, you won't find this plant outdoors in Tennessee.

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Last updated July 11, 2006